Fluridone: Principles of an Effective Aquatic Herbicide

Fluridone is a slow acting aquatic herbicide that diffuses throughout an entire water body and can take up to 30 days to begin controlling nuisance plants. However, water bodies treated with fluridone often stay weed free for 90 or more days. This is because fluridone stays suspended in the water for extended periods of time.

However, if there is overflow or outflow from a pond, then fluridone may not be as effective because the parts per billion (ppb) wouldn’t remain high enough for the full amount of time to kill the target plants.

When fluridone is absorbed by a plant, the plant’s ability to generate energy through photosynthesis is restricted. If the plant can no longer convert the sun’s light into energy, then it ceases to grow and subsequently dies off.

Because fluridone gradually kills plants over an extended period of time, the threat of oxygen depletion within the water body is avoided. Oxygen depletion occurs when a large amount of biomass within the water decomposes in a short period of time. Since fluridone kills the plants gradually, the resulting biomass decomposes at varying times instead of all at once.

Fluridone is an excellent control option for duckweed. Duckweed is a difficult to control plant because it rapidly and explosively reproduces. Traditional aquatic herbicides are not very effective because if only a small amount of duckweed survives, it can re-infest the entire surface of the pond. Since fluridone stays suspended in the water for long periods of time, most subsequent duckweed growth will also get treated.

Many submerged plants such as Hydrilla and watermilfoil can be treated with fluridone. This active ingredient also offers great control of water lilies. Because fluridone spreads throughout the whole body of water, it is most effective in smaller bodies of water such as ponds. If you are only interested in treating the weeds around a dock area, then a contact herbicide such as Dibrox diquat would be much better suited.

Fluridone is sold under numerous brand names and varying percentages. Lake Restoration’s Spritflo is 41.7% fluridone, the most concentrated on the market. Be sure to check the amount of active ingredient as well as the label to figure out how much of the product is needed. Amounts are based on average depth and acreage since the fluridone spreads throughout the water column.

Fluridone has no effect on algae. Because of this, it is recommended to use an algaecide such as Mizzen in combination with fluridone. These products work great together, and when combined, they control the majority of nuisances a pond will encounter.